thermal: Convert .get_temp() return value to millicelsius

thermal: Convert .get_temp() return value to millicelsius

Linux kernel .get_temp() callback reports values in millicelsius,
U-Boot currently reports them in celsius. Align the two and report
in millicelsius. Update drivers accordingly. Update callsites that
use thermal_get_temp() as well.

The 'temperature' command now reports temperature in millicelsius
as well, with additional accuracy. This changes command line ABI
slightly.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Reviewed-by: David Zang <davidzangcs@gmail.com>
[trini: Update test/cmd/temperature.c]
Signed-off-by: Tom Rini <trini@konsulko.com>